In casting certain automotive pistons, a reinforcing insert or strut is first positioned on a sectionalized mold core, a sectionalized permanent mold is closed about the core and molten aluminum is cast into the mold about the core. When the molten aluminum solidifies, the reinforcing strut remains captured in the cast piston to enhance the strength and thermal expansion characteristics of the piston.
The reinforcing struts typically are individual steel stampings supplied to the production casting line in a stack of identical struts nested one next to the other.
Heretofore in the production of strut-reinforced cast aluminum pistons, a stack of the steel reinforcing struts is placed in a vertical, tubular magazine for dispensing one by one to the core of the permanent casting mold. The reinforcing struts are fed successively by gravity to the open bottom end of the tubular magazine where a reciprocating stripper slide slides past the lower end of the stack to strip the lowermost strut from the stack and carry the stripped strut to a pick-up position. The stripped strut is transferred at the pick-up position from the slide to the mold core by a pivotal arm having a pick-up head with spaced apart pick-up magnets thereon. The pick-up head is lowered to pick up the stripped strut and carry it to the mold core for positioning thereon.
The type of strut dispenser described above suffers from numerous disadvantages. For example, the strut dispenser requires that the strut being stripped (removed) from the stack slide past the next adjacent strut in the stack. Since the struts are steel stampings with sharp corners and occasional burrs, sliding of the stripped strut can be obstructed and result in jamming of the strut in the magazine, resulting in a major source of production downtime to unjam the strut dispenser and causing unreliable operation of the strut dispenser. In some severe situations, the stamped struts must be subjected to a supplemental de-burring operation to achieve satisfactory operation of the strut dispenser in high production piston casting operations.
Moreover, variations in the thickness, flatness and surface roughness of the struts have been found to hinder satisfactory operation of the strut dispenser described above. In addition, variations in the height of the stack of struts as struts are dispensed changes the weight of the strut stack. This variation in the weight of the stack of struts has also been found to hinder satisfactory operation of the strut dispenser.